Very fast kinetic techniques are being used in our laboratory to delineate the conformational changes associated with the binding and turnover of erythrocyte carbonic anhydrase. Other developments concern our binding studies with sulfonamides, specific inhibitors of this hydrolyase. Work in progress also exploits our recent success, through modification studies, to identify the amino acid residues near or at the active site. Other aspects of our work concern the inhibition of carbonic anhydrase by various anionic inhibitors and its interaction with proteins and nucleic acids. Our recent work has appeared in Biochemistry, J. Phys. Chem., and J. Amer. Chem. Soc. Parallel work exploits our recent discovery that there are striking differences in carbonic anhydrase activity in solution and in the crystal. The relaxation times associated with the various elementary processes are being characterized in both H2O and D2O. The paradox associated with the high turnover rates of dehydration is being clarified through studies of the decarboxylation of HCO3-, DCO3- and related anionic analogues.